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>Remote sessions via XDMCP</A
></H1
><P
>Cygwin/X can be used login to one or several remote sessions
using XDMCP (X Display Manager Control Protocol).</P
><P
>Start Cygwin/X with a command similar to the following to login
to a single remote session using XDMCP:</P
><P
>&#13;<KBD
CLASS="userinput"
>X -query
<TT
CLASS="replaceable"
><I
>remote_hostname_or_ip_address</I
></TT
></KBD
>
</P
><P
>You may login to several remote sessions with a single or
multiple hosts using XDMCP.  Each session will need a separate display
number, specified by the <CODE
CLASS="parameter"
>:display_number</CODE
>
parameter, such as <CODE
CLASS="parameter"
>:0</CODE
>.  A display number is not
the same as a screen number, as a single display can have multiple
screens associated with it.  Each display listens on a different
network port number, so each display can connect to multiple machines.
Start Cygwin/X with command lines similar to the following to login
to several remote sessions using XDMCP:</P
><P
>&#13;<KBD
CLASS="userinput"
>X :0 -query
<TT
CLASS="replaceable"
><I
>remote_hostname_or_ip_address_0</I
></TT
></KBD
>
</P
><P
>&#13;<KBD
CLASS="userinput"
>X :1 -query
<TT
CLASS="replaceable"
><I
>remote_hostname_or_ip_address_1</I
></TT
></KBD
>
</P
><P
>Note that the <CODE
CLASS="parameter"
>:display_number</CODE
> parameter
is a general X Server parameter, not specific to Cygwin/X.  Further
documentation of the <CODE
CLASS="parameter"
>:display_number</CODE
> parameter
can be found in the <A
HREF="http://x.cygwin.com/docs/man1/Xserver.1.html"
TARGET="_top"
>X Server
manual page</A
>.  XDMCP is a complex system that is not specific
to Cygwin/X; further discussion of XDMCP is beyond the scope of this
document.  You may wish to read the <A
HREF="http://en.tldp.org/HOWTO/XDMCP-HOWTO/"
TARGET="_top"
>Linux XDMCP HOWTO</A
> or the
<A
HREF="http://x.cygwin.com/docs/man1/Xserver.1.html#lbAH"
TARGET="_top"
>X Server
XDMCP Options</A
> for more information.</P
><DIV
CLASS="note"
><BLOCKQUOTE
CLASS="note"
><P
><B
>Note: </B
>
For security reasons, XDMCP is not enabled by default on most modern UNIX distributions.
You will have to enable remote logins to your X Display Manager (<B
CLASS="command"
>xdm</B
>,
<B
CLASS="command"
>kdm</B
>, <B
CLASS="command"
>gdm</B
>, etc.).
See the configuration documentation for your X Display Manager and/or UNIX distribution.
The <A
HREF="http://x.cygwin.com/docs/faq/cygwin-x-faq.html#xdmcp"
TARGET="_top"
>Cygwin/X FAQ section on XDMCP</A
> may also be helpful.
</P
></BLOCKQUOTE
></DIV
><DIV
CLASS="note"
><BLOCKQUOTE
CLASS="note"
><P
><B
>Note: </B
>
XDMCP suffers from some of the same security problems noted in the previous section, but
unfortunately cannot be tunnelled over <B
CLASS="command"
>ssh</B
> due to it's use of UDP.  A
similar effect can be achieved with a command like
<KBD
CLASS="userinput"
>&#13;ssh -Y <TT
CLASS="replaceable"
><I
>remote_hostname_or_ip_address</I
></TT
> Xnest :1 -query localhost
</KBD
>
</P
></BLOCKQUOTE
></DIV
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CLASS="note"
><BLOCKQUOTE
CLASS="note"
><P
><B
>Note: </B
>
In some cases, e.g. if you have multiple network interfaces, it may be necessary
to use the <CODE
CLASS="parameter"
>-from <TT
CLASS="replaceable"
><I
>local_ip</I
></TT
></CODE
>
parameter to specify the local IP address to be used.
</P
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